State of the art diffusers can be classified in two major groups, namely, constant and variable throat diffusers. Constant throat diffusers are characterized by mechanical simplicity and low cost, but poor performance at high supersonic Mach numbers; their total pressure recovery is in general somewhat less than that of a straight shock which is, for example, at Mach 5 and about 6%. The diffusers with variable throat geometry are capable of much higher pressure recoveries, 20 to 30% at Mach 5; however, complexity and cost of such diffusers are very high. With the variable throat diffuser such means as actuators and sensors are needed to vary the throat geometry, which results in a comparatively slow overall response time.